from the GNU version of the Collaborative International Dictionary of English

n. One of the prepared entrails of an animal, esp. of a sheep, used for various purposes. See Catgut.

n. The sac of silk taken from a silkworm (when ready to spin its cocoon), for the purpose of drawing it out into a thread. This, when dry, is exceedingly strong, and is used as the snood of a fish line.

transitive v. To take out the bowels from; to eviscerate.

transitive v. To plunder of contents; to destroy or remove the interior or contents of.

from The Century Dictionary and Cyclopedia

To take out the entrails of; disembowel; eviscerate.

To plunder of contents; destroy or strip the interior of: as, the burglars gutted the store.

n. Either the whole or a distinct division of that part of the alimentary canal of an animal which extends from the stomach to the anus; the intestinal canal, or any part of it; an intestine: as, the large gut; the small gut; the blind gut, or cæcum.

n. In the plural, the bowels; the whole mass formed by the natural convolutions of the intestinal canal in the abdomen.

n. In biology, the whole intestinal tube, alimentary canal, or digestive tract; the enteric tube, from mouth to anus. See enteron, stomodæum, proctodæum.

n. The whole digestive system; the viscera; the entrails in general: commonly in the plural.

n. a strong cord made from the intestines of sheep and used in surgery

n. the part of the alimentary canal between the stomach and the anus

v. empty completely; destroy the inside of

n. a narrow channel or strait

v. remove the guts of

Etymologies

From Middle English guttes, entrails, from Old English guttas; see gheu- in Indo-European roots.

(American Heritage® Dictionary of the English Language, Fourth Edition)

From Middle English gut, gutte, gotte, from Old English gutt (usually in plural guttas ("guts, entrails")), from Proto-Germanic *gut-, from Proto-Indo-European *gʰeud- (“to pour”). Related to English gote ("drain"), Old English ġēotan ("to pour"). More at gote, yote. (Wiktionary)

Examples

June 22nd, 2009 3: 51 pm ET this gut is a liberal clown and acted like a republican and cheated on his wife but he is not responsible because he is a hypocrite democrat.

Even the people defending voting for the Democrats on this turn of the wheel defend it as 'pragmatic', as though choosing to be stabbed in the gut is the pragmatic alternative to choosing to be shot in the head.

Q: A writer has crafted a book he believes in his gut is a breakout novel: it has it all, including a unique setting, authentic characters, a captivating plot that unfolds in surprising ways, scads of conflict and more.